This article first appeared and is reproduced here with the kind permission of Standart magazine, You should pick up issue 35 to see this in print alongside articles from Dr Fabian Carvalho and Lance Hedrick.

Fermentation and coffee go hand in hand. The simplest way to remove the pulp of the fruit without damaging the bean is to ferment it, but doing so breaks down the structure of the pulp and can affect the flavour in the bean. The current trend towards non-traditional fermentation is a way for producers to add value to their crop, but the practice entails increased expenses and risk. Sometimes, however, it works out very well indeed. Let’s take a closer look at a simplified fermentation method author Mat North believes could be deployed elsewhere, at low cost and to great effect.

There is beauty in simplicity, but it’s nevertheless difficult to achieve; it takes a creative and open mind to distil something complex to its barest bones. After all, how can we show how hard we have worked if the process isn’t complicated? This is a story about the search for simplicity, the journey to discover it, and—after all, this is Standart—a fermentation process called the anoxic water pillow technique.

Enter Miguel Fajardo Mendoza, a fourth-generation farmer from Finca Santa Helena, a family farm sat among the hills of Risaralda in the central coffee heartlands of Colombia. The farm had done well enough for Miguel to pursue an education in industrial engineering and apply his knowledge as the owner of a microbrewery before returning to the family business.

Coffee and beer have gone together for as long as most of us can remember, and the parallels extend beyond the obvious similarities between the craft brewing movement and specialty. For example, consider the plethora of solutions to tune our water for brewing coffee. Recipes are available to accentuate mouthfeel, acidity, sweetness, floral notes—the list is endless. This, however, is nothing more than ‘Burtonisation’—a term first coined in 1882 to describe the practice of adding gypsum and various sulphates to water, imitating the famed beer-brewing waters of Burton upon Trent in England. So popular were the beers, in fact, that in 1830 Burton brewers fought a libel suit against those falsely accusing them of adulterating their beers to enhance the flavours.

The irony of a tale about simplicity that has taken a detour is not lost on me, but I promise you it’s relevant. Perhaps the most pertinent link between the two and the one that truly ties together Miguel’s education, career as a brewer, and life in coffee is fermentation.

In 2011 Miguel and his friend Mario Fernández started working at Finca Santa Helena, with the goal of understanding fermentation and improving crop quality, but they quickly ran into a scaling problem. The nature and size of the vessels—cement tanks 54 cubic metres in volume and lined in traditional majolica tiles—made it difficult for two reasons. Firstly, it is not easy to control the heat generated when attempting to prolong the fermentation timeframes for such a large volume, and secondly, by this time production at the farm was declining so the tanks were much larger than the available harvest. Despite their work, Finca Santa Helena did not survive, primarily due to the termination of the International Coffee Pact (ICP) in 1988. Farms designed for medium-scale production profited during the years of the ICP but were ill-equipped for the new reality of a more volatile and fluctuating market. Attempts were made to pivot production towards organic-certified output, but a few years later it was no longer viable financially and had to be sold.

Throwing himself into brewing led Miguel to new insights. You see, when it comes to fermentation, control is everything and control of temperature especially so. His training as an industrial engineer helped with cooling systems, material properties, and measurement techniques. Beer, like coffee, has a fermentation stage, and also like coffee it is very fickle when it comes to temperature. For example, the ideal temperature for brewers’ yeast (saccharomyces cerevisiae) is approximately 17–24 C. Too cold and the fermentation stalls; too hot and you can quickly generate overly sour flavours or kill the yeast. In both circumstances, the batch is ruined.

 But life works in funny ways and coffee has a way of bringing you back in. In 2011, purely by chance he met his future partners in what was to become Raw Material Coffee, a social enterprise founded with the aim of empowering economic freedom for producers. Like many modern stories it started on Facebook and a chance invitation to visit a farm that happened to be Finca Santa Helena. At the core of this new company was El Fénix, a run-down farm in Quindío, Colombia. Intended as a community wet mill and funded via an internationally successful kickstarter, it grew into a test bed for research into agronomy and fermentation to provide simple, practical, and thoroughly tested methods that producers could use to add value to their crops.

At this time, the coffee world began changing rapidly. The new generation of producers were, like Miguel, looking beyond traditional knowledge bases and into complementary fields for inspiration. In 2015 a Sudan Rume processed using carbonic maceration—a winemaking process whereby grapes are fermented in a carbon dioxide-rich environment before crushing—achieved a first-place finish in the World Barista Championship, and the floodgates were opened. It’s a well-known adage in motor racing that ‘what wins on Sunday sells on Monday’, and this was the case in processing as competitors searched for the next new thing and customers wanted to try the coffees being judged as exceptional. And so in the years that followed there was a rise in anoxic fermentations, co-ferments, Koji inoculation, thermal shock, saline washes, and flavour additives—a blizzard of ways that a producer can take a simple variety and, by some clever processing, add value. At El Fénix, Miguel and Raw Material had the perfect place to experiment on a new fermentation method that would add value for the producers while remaining simple and replicable.

If this article were a film, we’d have a montage scene at this point. Jump cuts and wipes of testing and failure, testing and failure, before the eureka moment and everyone high fives; but it’s not, and the process was longer, more laborious, and driven by one key fact: It had to be easily replicable. In reality, this means it had to be simple.

Controlling fermentation temperature isn’t easy, and utilizes the zeroth law of thermodynamics, which states that if we expose two systems whether of solid, liquid, or gas of differing temperatures to each other, they will try to reach an equilibrium. The ability to raise or lower the temperature and the mechanisms needed to do this, as well as the vessels and tanks used by larger farms and in other industries, are expensive. Custom-built metal tanks stored in temperature-controlled environments or cooling pools of liquid continuously flowing around the tanks are just two examples.

So Miguel turned to his experience in brewing and engineering. Brewing had taught him the importance of controlling the fermentation and the necessary complex systems, while the engineer in him allowed him to answer a crucial question: On a farm in the Colombian mountains, what free resource with good heat transmission properties is at hand? Water.

At the start, proposed solutions were too complex or required large equipment. Cooling coils made from hosepipe and submerged into fermenting coffee were too thick to leach away heat and became far too dirty. Adding cold water directly to the fermenting beans, similarly to how ice is added to sake fermentation tanks, only served to dilute the substrate and change the flavour profile, sometimes to the detriment of the coffee by making it flat and muted. Dipping the tank in a large tub of cold water was possible, but practically difficult to replicate on a small scale.

Eventually, what it took was stepping back and looking at the materials at hand. Miguel asked himself: ‘What are the simple things almost every producer has that we can use?’ A tub or tank, some plastic sheeting, and a little water. It seems almost too simplistic, but it worked; and like all simple things, it was the result of years of trial and error.

Firstly, attach a tap to or make a small hole in the bottom of your tub to allow some of the fermentation juices to escape. This helps to maintain the fermentation substrate and adds clarity to the acidity. Next, add your coffee as cherry or pulped, depending on whether you’re going to dry it as a natural or washed, floated to remove lower-density beans. Take the plastic sheeting and place it over the coffee, allowing it to extend above the top of the tub. Then fill the rest of the tub with water. 

The sheet provides a barrier between the water and the coffee and is thin enough to allow the water to fill the shape of the tub, forming a pillow of water above the coffee. The water here serves two functions: Firstly, it creates an anoxic fermentation environment, one low in free molecular oxygen, and secondly, the water in this state acts as a large heatsink to draw heat away from the fermenting coffee, which regulates the risk of developing off flavours and aids in prolonging shelf life.

The anoxic water pillow technique is a creative use of basic materials to make a complex process so simple that it can be utilized anywhere in the world. The proof of such simplicity is always shown by how easily others can understand and implement the concept.

Following years of use at El Fénix and the Raw Material processing station Jamaica in Caldas, Colombia, it was put to the test during the COVID-19 pandemic. Miguel and the team at El Fénix exchanged videos and messages with their counterparts at Izuba, Raw Material’s washing station in Burundi, ahead of the 2020 harvest. There could be no second chances; the risk of spoiling a significant portion of the crop was great, and Miguel was unsure whether they could communicate this simple process without being there in person.

Put simply, yes they could. When the samples were milled, the results were astounding, adding layers of complexity and flavour. The years of refining the process at El Fenix had achieved its goal; it truly was a complex process reduced to something simple enough to implement anywhere in the world.